Blocking of primary in vitro antibody responses to thymus-independent and thymus-dependent antigens with antiserum specific for IgM or IgD.

The effect of anti-mu and anti-delta on the primary in vitro IgM response of murine splenocytes to thymus-dependent (trinitrophenylated erythrocytes) and thymus-independent (trinitrophenylated brucella) forms of trinitrophenyl was studied. The results indicate that either anti-mu or anti-delta can block the response of adult splenocytes to the thymus-dependent antigen. The thymus-dependent responses of neonatal splenocytes that bear a low concentration of IgD were also abrogated by treatment with anti-delta. In contrast, anti-mu, but not anti-delta, blocked the response of adult splenocytes to the thymus-independent antigen used. These results indicate that both IgM and IgD are receptors required for triggering cells by a thymus-dependent antigen but that only IgM receptors are required for triggering by the thymus-independent antigen used.